Such a ski binding is described in the WO 87/03211 (corresponding to U.S. Pat. No. 4,993,742). The swivel part in this known ski binding is designed as a toggle lever and can, in the closed position of the binding, be swivelled together with the holding cup against the force of an elastic element. Such a cross country ski binding with the cross country ski boot fitting said binding is commercially available and has proven to be successful.
The elastic element is in this known cross country ski binding arranged in front of the swivel part and is supported on an upwardly directed arm of the swivel part. The elastic element itself is designed as a plastic block. This plastic block rests in the non-stressed position of the binding flat on the forwardly directed side of the swivel part. The swivel part together with the holding cup is swivelled upwardly during the walking movement, with the elastic element being compressed. The point of application of the respective restoring force changes during the swivelling caused by the swivelling movement and the change in form of the compressed elastic element. Furthermore, a problem results with the use of plastic springs in that the spring action is, among others, influenced by the outside temperature. Furthermore, plastic springs age relatively quickly under the influence of the weather and sun and must then be replaced.
A similar ski binding in EP-A2 0183000 suggests a use of a compression spring as the elastic element. However, this compression spring is also arranged in front of the swivel part and is supported on its forwardly directed side. Therefore, this known ski binding has also the problem of not exactly defining a point of application of the restoring force. Furthermore, the spring is subjected to weather and in particular to dirt and ice.
The purpose of the invention is to avoid the disadvantages of the known ski bindings and to design a ski binding of the above-mentioned type such that the restoring force of the spring is applied to a point selectable by the designer and also the spring characteristic can be designed selectively and is essentially independent of outside influences, like temperature, weather and dirt.